"I am travelling to CDG and return via QF/BA in N class next month - on the way home I am on BA 17 LHR-MEL, under the new QF FF rules i will only receive 25% points and was thinking of looking at other programs to drop these points and earn SC's."

If you can do it, I would suggest changing it to be booked on the QF codeshare number. That way you will get 100% miles plus 100% WP bonus rather than 25% + 25% into a QF account

If crediting to AA, you would be able to achieve Platinum status ( OW Sapphire ) from the round trip. If booked on BA flight #, you will get 25% miles outbound plus 25% + 25% platinum bonus on the inbound ( i.e. the bonus is 100% of the earned 25% ) ( approx 2500 + 7500 = 10000). If you were able to change to a QF flight # your earning would be doubled

Dave